The presence or absence of cell surface antigens (A,B,H) on the cell surface of bladder tumors is studied. The major blood group antigens A,B, or O (H) are present on normal bladder epithelium but are not present on some low grade and low stage papillary transitional cell carcinomas of the bladder. In this study we have demostrated that of Stage A bladder tumors that have not recurred in at least 5 years, 3 of 5 have retained the cell surface antigens while tumors that have recurred locally or invaded or metastasized had lost these cell surface antigens on the original Stage A tumor. We are attempting to correlate these cell surface antigens with various histopathological grades and stages of the bladder tumor.